The use of cationic lipids to deliver nucleic acids into cultured cells was first described by Felgner and co-workers (Proc. Nat'l Acad. Sci. 84, 7413 (1987)). Subsequently, Behr (Proc. Nat'l Acad. Sci. 86, 6982 (1989)) showed that polycationic lipids also can be effective delivery agents. Large number of cationic lipid reagents have now been described and several of these reagents are commercially available, for example, LipofectAmine, LipofectAmine 2000, Fugene, TransfectAm, Lipofectin and DOTAP. None of these reagents, however, is universally effective on all cell lines and none is as effective as viral based gene delivery systems. In addition, most of the reagents are toxic in some degree to the cells being transfected.
Accordingly, there still exists a great need for the development of transfection reagents that are less toxic than those currently available but that are highly efficient and more universally applicable for transfecting a wide variety of cell types. Ideally, such a reagent will have minimal safety risk and immunogenicity when compared to viral based delivery systems. The successful development of such a reagent will have a profound impact in biotechnology in general and gene therapy in particular.